DETERMINATION OF DUCTILITY AND DEFORMABILITY INDICES FOR FRP STRENGTHENED RC SLABS

An experimental study was conducted to investigate the behaviour of retrofitted reinforced concrete (RC) slabs under short-term static load. Eight slabs (3.0 m x 0.5 m x 0.1 m) were load tested to ultimate failure. All slabs were initially identically reinforced, two were used as control and the rest were externally bonded with carbon fibre reinforced polymer (CFRP) sheets or pultruted plates. The slabs were seen to behave significantly differently from that of typical CFRP strengthened RC beams, where concrete cover tearing-off or other premature failure modes are often observed. It was found that the load carrying capacities of the CFRP strengthened slabs greatly increased by up to 458%. The maximum surface crack width of the strengthened slabs was noted to be within the normal serviceability limit until approaching the final failure. The average crack spacing in the constant moment zone was much smaller when compared with those of the unstrengthened control slabs. It was shown that the CFFR strengthened slabs exhibit reasonably ductile behaviour even though a high proportion of elastic stored energy was evident at ultimate failure. A numerical model was used to predict the slab behaviour under the serviceability and ultimate loads, which showed excellent agreement with the experimental results. In conclusion, RC slabs are well suited for strengthening by externally bonded FRP composites. In an optimised design, the strength of FRP strengthened RC slabs can be significantly increased, whilst the ductility of such elements can still be maintained at an acceptable level so that no catastrophic brittle failure would occur.

• INTRODUCTION

• EXPERIMENTAL PROGRAMME

• EXPERIMENTAL RESULTS

• DUCTILITY

• NUMERICAL MODELLING

• DISCUSSIONS AND CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES